This application is based on Japanese patent application, No. JPAP2001-004338 filed on Jan. 12, 2001, in the Japanese Patent Office, the entire contents of which are incorporated by reference herein.
1. Field of the Invention
The present invention relates to a method and apparatus for reading an image, and more particularly to a method and apparatus for providing effective grounding to eliminate or reduce unwanted electromagnetic interference occurring in driving a light source of an image reading apparatus.
2. Discussion of the Background
Conventionally, image reading apparatuses (such as scanners, etc.) drive a light source with a driving voltage having a sign waveform by using a driving voltage generator (e.g., a light source stabilizing apparatus) connected to the light source through a flexible printed wiring plate. This driving method does not result in a substantial amount of EMI (electromagnetic interference).
However, a pulse-wave form driving voltage is now commonly used because a light source driven with a pulse-waveform generates a larger amount of light. A problem with this type of method is unwanted radio noise (EMI) occurs because the pulse-waveform driving voltage has a steep change in its waveform. Therefore, it is difficult to suppress the amount of radio noises to meet certain EMI requirements.
One attempt to reduce unwanted radio noises occurring with the pulse-waveform driving method is to shorten a distance between the light source and the driving voltage generator by mounting the driving voltage generator to a frame or a carriage holding the light source.
However, mounting the voltage generator in this way increases a total weight of the frame or the carriage. Further, the load required by the motor to drive the frame or the carriage is increased. Accordingly, a motor with a larger torque is needed, which also increases the amount of electricity needed to drive the motor. In addition, the cost of the motor and the power consumption is also increased.
Accordingly, one object of the present invention is to solve the above-noted and other problems.
Another object of the present invention is to provide a novel image reading apparatus and method that is reduced in size and cost, and that reduces unwanted radio noise to meet certain EMI requirements.
The present invention solves these and other objects by providing a novel image reading apparatus including a frame for moving in a reciprocating fashion, a light source held by the frame for emitting light so as to irradiate an image surface of an original, and a photo-electronic converting element for receiving the light reflected by the image surface of the original and for converting the received light into an analog image signal. Also included is a flexible plate having a first printed wire for applying a driving voltage to the light source, and having a second printed wire for establishing a ground to the frame. The present invention also provides a novel image reading method.